Controller cards are IDE, PCI, or PCI-Express cards, or even USB devices, that add functionality to your system. There are all kinds of controller cards, from RAID controllers to USB, SATA, and more. If your system is missing a port or certain device compatibility, install a controller card to add the ports or compatibility that you need.

Upgrade your computer system's capabilities with an add-on card. Add on cards plug into an available expansion slot on your motherboard to give you access to new interfaces - such as USB, Firewire, etc.